Bride of Zen problem

[arold19]

I use (good) capacitor by Solen, there are 630 V value ......
I use the same pot of my first preamplifier and my first doesn't make noise....
On my First Preamp, I but an 100 k resistor in serie because the cd player signal was to strong.. ( I reed that on the forum)
On this preamp, I put an 75K resistor to have more gain to drive my Zen V4 !!! Can this make the noise ???

Anorgan: I don't know any grounding issue !!!!! Now, the preamp in NO grounding at all..... I have to put the negative point at the ground ??? And What is the double ground ???

Thank you for trying help me !!!

 

[arold19]

How I have to ground the preamplifier to correct the noise ????

 

[Anorgan]

I don't have my boz grounded too, but it is not advisable. To ground it, do the following. Take nice strong wires (telephone shielded cable for that) and connect the ground (every (-) pole) from ONLY ONE place (so you don't double ground) to the mains (ground). Also, don't connect anything before you read more posts about hum and ground issues, and by all means, read Grounding article by mr. Pass. It can be found on www.passdiy.com. Try to measure voltage beetwean GND on BOZ and mains socket ground. Don't, if you don't know what you're doing. Also, (if you can cranck the volume up to the top) try to bridge (just put a peace of wire to connect the signal path) the volume pot. If that helps - pot is bad. Try to put boz as a preamp to some comercial amp you have (i'm running it on a Marantz 2220). If that helps - Zen has the hum. Post your results - maybe we can solve the problem.

 

[arold19]

The problem is that: " when I put the volume at 50%, there almost no hum but if I crank the volume more than 60%, the hum begin to be very very loud..... so I will try to do what Anorgan say..... and I come back to this...

 

[arold19]

I tried to ground the BOZ and there no difference !!!
I tried also to connect the output capacitor to my amplifier, so, I bypass the potentiometer, and there so difference, there still a noise !!!!
I read the arcticle of Nelson Pass about the ground loop but I don't know what to do !
So, the sound of the Premp is great, the noise appear at high level but I am a little bit dissapointe by the "performance" at high level !!!
If I can do something to correct that, please send me a message !!

Thank you !!

 

[Anorgan]

You say you have 2 Boz's - put power circuit from the good boz to this one that has the noise. If you made it all on one board, you'll have a bit of a problem - remember those resistors? Pull one end out, and get 60V out of that. If you don't know what I'm talking about ask me, don't do anything.
How loud is the noise, anyway?Can you hear it when it plays music?

 

[arold19]

I'm not sure about what you are talking !!!!
I have 2 BOZ and 2 separated power supply.... do you want to put the circuit of this BOZ on the power supply of the other ???
At full volume, I can hear the noise "well" at 2 meter.... it is sure that I don't listen the noise when I listen music at this level, the sound is very very loud.... maybe between two tracks, but I don't listen music so loud everytime !!

 

[Anorgan]

So the noise doesn't get louder or quieter, it's just there - how far is your trafo from your BOZ? Try putting it FAR away - what happens when you unplug the trafo from the mains (the boz should play a while - try hearing the noise then - when the trafo isn't running)

I have 2 BOZ and 2 separated power supply.... do you want to put the circuit of this BOZ on the power supply of the other ???

Yes - try out the power suplies - maybe they aren't the same (you had problems with them).

 

[arold19]

My tranfo is a Pliton..... it is far away from the circuit and if I unplug the transfo of the main, the BOZ continu to play for maybe 5 sec and the noise stay at high level

I will try the other power supply

 

[Anorgan]

If you have separated boards for power suply and boz - maybe the wires aren't good, or it could be the power suply - you say this boz is your father's - maybe electrolites have gone old,dry, or whatever (i'm not familiar with age troubles, someone else might describe them better).

 

[arold19]

I tried my other power supply and the noise gone !!!!
So, with the other power supply, I have no noise at the output, even at max level ! So now, the problem is the power supply but I realy don't know how to correct that !!! I use the same transfo, the same transistor, I only use 3 zener of 20 v but I don'"t think that this can make differente.....
Please, what I have to check ???

thank you !!!

 

[till]

you have to post a drawing of you power supply circuit _exactly_ like you built it.

you have to post a picture of it.

if you tell "i built like in the article" it will not help, because like in the article it works.

 

[arold19]

I made a dram on "paint" of my "board" but the image is to big, I can't put it on the forum, how I can do to reduce this image ????

 

[till]

there you are:

(arolds drawing)

 

[till]

i suspect

a) your zehners are crap

or

b) a cap is crap

or

c) the transistor is damaged

 

[arold19]

Yes but it work !!!!!
For R2 and R3 I use 52 ohm resistor, and there 2 V between each when the circuit is connect !! !!! This is normal ???

 

[till]

between which points exactly???

across the R´s ? this should depend on the current flow.

 

[Peter Daniel]

BOZ is quite sensitive to wiring and ground layout. I had a problem with hum as well and I spent almost 2 days rearanging everything, untill it bacame hum free. So you have to experiment. Try to layout the ground paths as simple as possible, shield the cabinet and connect everything directly to mains earth. It worked in my case.

And don't call it "bridge"

 

[Anorgan]

I'm glad I helped. But now for the noise free power suply - if you have 2 trafo's - try them out, maybe caps are bad, replace them, if you can, put two caps in parallel instead of one - this reduces capacitive resistance, helps a bit - you know what happens with capacitance when you parallel 2 capacitors? Measure every zenner diode - the voltage accros a zenner should be <>20V. If you did point-to-point wireing - try replacing wires, try different layout - ground wire should be short.

 

[arold19]

I found the problem of my Bride Of Zen noise....
It is the Plitron Transformer.... I try to change my other transfo in my new circuit and the noise gone... And if I put my last transfo in the old circuit, the noise apper.... so, I have two identical Plitron Transformer and one of the two is very noisy....

I have this transfo since 2 month.... now I will contact the manufactured... and I don't know what will happen.....

Do you have any adea ??